<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        body{
            background: #cccccc;
        }
        .box2{
            height: 50px;
            width: 200px;
            margin: 100px auto;
            display: flex;
            justify-content: space-evenly;
        }
        .dian-1,.dian-2,.dian-3{
            height: 50px;
            width: 50px;
            background: white;
            border-radius: 50%;
        }
        .dian-1{
            animation: myfist .3s linear alternate;
            animation-iteration-count: infinite;
        }
        .dian-2{
            animation: myfist .4s linear alternate;
            animation-iteration-count: infinite;
        }
        .dian-3{
            animation: myfist .5s linear alternate;
            animation-iteration-count: infinite;
        }
        @keyframes myfist {
            from{

            }
            to{
                transform: scale(.4);
            }
        }
    </style>
</head>
<body>
<div class="box2">
    <div class="dian-1"></div>
    <div class="dian-2"></div>
    <div class="dian-3"></div>
</div>
</body>
</html>